package com.data.basic.chapter09.leetcode;

import com.data.basic.chapter09.Merger;
import com.data.basic.chapter09.SegmentTree;

/**
 * leetcode 303
 */
class NumArray2 {

    private int sum[];//sum[i] 存储前i个元素和，sum[0]=0而不是第0个元素
    //sum[i]存储 nums [0...i-1] 的和

    public NumArray2(int[] nums) {
        sum = new int[nums.length+1];
        sum[0]=0;
        for (int i=1;i<sum.length;i++){
            sum[i]+=sum[i-1]+nums[i-1];
        }
    }



    public int sumRange(int i, int j) {
        return sum[j+1]-sum[i];
    }
}